/*
 * Speed Fraction
 * by: Charlton Harrison
 * Computes the best approximate fractions for a decimal
 */

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>

/* #include <math.h> */
#include <gmp.h>

/* for kbhit() */
#include <sys/time.h>
#include <unistd.h>

/* Function for kbhit() - the gcc way */
/* Only works for the <return> key though... */
int kbhit()
{
    struct timeval wait;
    int ret;
    fd_set readfd;

    FD_ZERO(&readfd);
    FD_SET(0, &readfd);
    wait.tv_sec  = 0;   /* Wait zero seconds */
    wait.tv_usec = 0;
				    
    ret = select(1, &readfd, NULL, NULL, &wait);
    return(ret);
}


int main(int argc, char *argv[])
{
    int kcount=0;
    mpz_t lpa, lasta, lastb, a, b, c, e, t, tai, tbi, last10;
    mpf_t m, p, lastp, x, h, fe, ft, taf, tbf;

    mpz_init(lpa);    mpz_set_ui(lpa, 0);
    mpz_init(lasta);  mpz_set_ui(lasta, 0);
    mpz_init(lastb);  mpz_set_ui(lastb, 0);
    mpz_init(a);      mpz_set_ui(a, 0);
    mpz_init(b);      mpz_set_ui(b, 0);
    mpz_init(c);      mpz_set_ui(c, 1);
    mpz_init(t);      mpz_set_ui(t, 0);
    mpz_init(e);
    mpz_init(tai);
    mpz_init(tbi);
    mpz_init(last10);

    mpf_init(m);      mpf_set_d(m, 0.5);
    mpf_init(p);      mpf_set_d(p, 0.0);
    mpf_init(lastp);  mpf_set_d(lastp, 0.0);
    mpf_init(x);
    mpf_init(h);
    mpf_init(fe);
    mpf_init(ft);
    mpf_init(taf);
    mpf_init(tbf);

    /* Initializations */
    if (argc != 2) {
	printf("Usage: spfrcn [decimal]\n");
	exit(1);
    }

    printf("\nHit return at any time to stop...\n");

/*    x = atof(argv[1]);   */
    mpf_init_set_str(x, argv[1], 10);

/*    printf("Ok: %.16f\n", x);   */
    mpf_out_str(stdout, 10, 32, x); printf("\n");

    while (1) {						/* Main Loop */

/*	t++;  m+=x;  e=m;   */
	mpz_add_ui(t, t, 1);  mpf_add(m, m, x);
	mpz_set_f(e, m);

/*
mpz_out_str(stdout, 10, e); printf("  :  ");
mpf_out_str(stdout, 10, 0, m); printf("\n");
*/

/*	h=((double)e / (double)t);   */
	mpf_set_z(fe, e);  mpf_set_z(ft, t);
	mpf_div(h, fe, ft);

/*
mpz_out_str(stdout, 10, e); printf(" / ");	
mpz_out_str(stdout, 10, t); printf("  :  ");
mpf_out_str(stdout, 10, 0, h); printf("\n");
*/

	mpf_sub(taf, h, x);  mpf_sub(tbf, p, x);
	mpf_abs(taf, taf);  mpf_abs(tbf, tbf);
/*	if (fabs(h-x) < fabs(p-x)) {   */

/*
mpf_out_str(stdout, 10, 0, taf); printf(" -:- ");
mpf_out_str(stdout, 10, 0, tbf); printf("\n");
*/

	if ((mpf_cmp(taf, tbf)) < 0) {
/*	    p=h;  a=e;  b=t;   */
/*printf("here0\n");*/
	    mpf_set(p, h);  mpz_set(a, e);  mpz_set(b, t);
	}

/*	if (a != lpa) {   */

/*
mpz_out_str(stdout, 10, a); printf("=?");
mpz_out_str(stdout, 10, lpa); printf("\n");
*/

	if ((mpz_cmp(a, lpa)) != 0) {
/*	    if (h==x) {   */
	    if ((mpf_cmp(h, x)) == 0) {
/*		printf("%ld / %ld  :  %.16f\n", a, b, p);   */
		mpz_out_str(stdout, 10, a);  printf(" / ");
		mpz_out_str(stdout, 10, b);  printf("  :  ");
		mpf_out_str(stdout, 10, 0, p);  printf("\n");
		exit(1);
	    }
/*	    last10 = pow(10, ((int)log10(e)));   */
	    mpz_ui_pow_ui(last10, 10, (mpz_sizeinbase(e, 10) - 1));
/*	    if ((int)(e/last10) != (int)(a/last10)) {   */

/*
mpz_out_str(stdout, 10, e); printf("  :  ");	
mpz_out_str(stdout, 10, a); printf("  /  ");
mpz_out_str(stdout, 10, last10); printf("\n");
*/

	    mpz_tdiv_q(tai, e, last10);  mpz_tdiv_q(tbi, a, last10);

/*    
printf("here1\n");
mpz_out_str(stdout, 10, tai); printf("  =?  ");	
mpz_out_str(stdout, 10, tbi); printf("\n");
*/

	    if ((mpz_cmp(tai, tbi)) != 0) {
/*		printf("%ld / %ld  :  %.16f\n", a, b, p);   */
		mpz_out_str(stdout, 10, a);  printf(" / ");
		mpz_out_str(stdout, 10, b);  printf("  :  ");
		mpf_out_str(stdout, 10, 0, p);  printf("\n");
/*		lpa=a;   */
		mpz_set(lpa, a);
	    }
	}

	kcount++;
	if (kcount==1000) {     /* every 1000 loops check to see if kbhit */
	    kcount=0;
	    if (kbhit()) {
		exit(1);
	    }
	}

    }						/* End of Main Loop */

}